Marijuana
- The literature does not support marijuana as treatment for psychiatric disorders: though THC and CBD have been suggested to have a role in treatment of psychiatric conditions, a meta-analysis of 83 studies (40 RTCs; n = 3067) found only scarce evidence to suggest cannabinoids improve depressive disorders and symptoms, anxiety, ADHD, Tourette, PTSD, or psychosis, and overall did not find sufficient evidence to recommend marijuana products as treatment in psychiatric conditions (Black et al, 2019)
- Marijuana intake significantly prompted lower self-efficacy (initiative and persistence), supporting cannabis amotivational syndrome by McGlothlin and West. Results are supported even after controlling many covariates including demographic, personality traits, alcohol use, and tobacco use (Lac and Luk, 2018).
- Cannabis and cognitive impairment:
- Causes acute impairment in domains of learning and memory, attention, and working memory (Volkow et al, 2016)
- After a month of abstinence, neuropsychological testing of heavy cannabis users becomes comparable to non-users, though use at an early age is linked to greater neuropsychological deficits (Volkow et al, 2016)
References
Black, N. et al. Cannabinoids for the treatment of mental disorders and symptoms of mental disorders: a systematic review and meta-analysis. Lancet Psychiatry 6, 995–1010 (2019). https://pubmed.ncbi.nlm.nih.gov/31672337/
Lac, A. & Luk, J. W. Testing the Amotivational Syndrome: Marijuana Use Longitudinally Predicts Lower Self-Efficacy Even After Controlling for Demographics, Personality, and Alcohol and Cigarette Use. Prev. Sci. Off. J. Soc. Prev. Res. 19, 117–126 (2018). https://pubmed.ncbi.nlm.nih.gov/28620722/
Volkow, N. D. et al. Effects of Cannabis Use on Human Behavior, Including Cognition, Motivation, and Psychosis: A Review. JAMA Psychiatry 73, 292 (2016). https://pubmed.ncbi.nlm.nih.gov/26842658/
